Decorating synthetic resin panel



Dec. 1, 1964 J. s. FINGER 3,159,525

DECORATING SYNTHETIC RESIN PANEL Original Filed Jan. 21, 1955 3Sheets-Sheet 1 IN VEN TOR.

ATTORNEKS Dec. 1, 1964 J. 5. FINGER DECORATING SYNTHETIC RESIN PANELOriginal Filed Jan. 21, 1955 3 Sheets-Sheet 2 wmmzdjmo Dec. 1, 1964 .1.s. FINGER 3,159,525

DECORATING SYNTHETIC RESIN PANEL Oiiginal Filed Jan. 21, 1955 sSheets-Sheet 3 EAST MAN United States Patent Patented Dec. 1, 1964 toprovide a thermosetting resin product having novel decorative elfects onone or more of its surfaces.

It is a further object of the present invention to provide a novelthermosetting resin product having a unique decorative crinkle finishthereon, which product may b 7 translucent and may be tinted withsuitable dyes or pig- This invention relates to synthetic resin articlesof manufacture and more specifically relates to synthetic resin panelshaving novel decorative surfaces.

This application is a division of my copending application, Serial No.483,381, filed January 21, 1955, noW Patent No. 2,959,511, having beenissued on November 8, 1960, which is a continuation in part of myapplication, Serial No. 227,144, filed May 21, 1951, now abandoned.

Various thermosetting resin, such as the polyesters, polyester-styreneblends, phenol-formaldehyde, alkyds and the like, shrink or contract oncongealing from their plastic or fiuid state to a solid form. Suchshrinkage or contraction occurs either where a filler such as glassfibers is incorporated in the resin, or where the filler is omitted.conventionally, in producing reinforced thermosetting resin panels forvarious structural uses, such as for skylights, paneling, awnings, walland ceiling elements and the like, a thin film, such as regeneratedcellulose (known in the trade as cellophane), is placed on oppositesurfaces of a layer of liquid thermosetting resin having a reinforcingfiller incorporated therein, and the wet lay-up so formed is placed on asuitable mold and cured. By this procedure, a smooth finish is producedon opposite surfaces of the cured product inasmuch as the cellulose filmshrinks to substantially the same degree as does the resin interlayerduring the curing operation.

The present invention is based on the discovery that by employing filmssuch as, for example, certain types of cellulose acetate films, whichare affected by liquid resins or by atmospheric moisture, to encase theresin interlayer, there is provided an excess of film which crinkles asthe interlayer is cured. The crinkles provide substantially uniform,solidified crinkled lines in the interlayer and thereby produce a highlydecorative pattern or finish on the surface of the cured product. Afterthe resin interlayer is cured, the films are stripped therefrom and aproduct having a highly decorative surface finish is provided. I

The exact reasons why these selected films react in the foregoing mannerare not presently known. One theory is that shrinkage of the resininterlayer occurs due to chemical reaction therein during curing. Inaddition, it appears that there might be a certain amount of elongationof the film during the curing operation. The elongation may be due toatmospheric moisture affecting the film or to the fact that certainchemical constituents of the liquid resin in the interlayer have atendency to attack and partially dissolve the film, or to attack orpartially dissolve the plasticizers used in the film to such an extentthat the original fiat form of the film is changed to an irregular formby the solvent action. This chemical attack is thought to stop shortlyas the resin interlayer is cured since most components of thermosettingresins become chemically bonded and are rendered chemically inert whenthe resin is cured. However, the net result is that the cured resinproduct has an excess of film covering it which crinkles the resinduring gelation. When the film is removed, the crinkled finish remainspermanently on the product.

Accordingly, it is an object of the present invention merits.

In accordance with the present invention, a thermosetting resin inliquid state is placed upon a thin synthetic organic film which isappreciably affected either by moisture or by the thermosetting resin. Afiller or reinforcement, such as random mat glass fibers, is thencombined with the resin and a second similar film is placed on thecombined resin and filler mix to form a wet lay-up. The film-encasedassembly is thereafter transferred to an appropriately shaped mold andcured by heating in a well-known manner, to a hard, solid state.

During the curing stage, the thermosetting resin shrinks substantiallyand the film encasing the assembly, either because of chemical attackand/ or the effect of moisture appears to expand. Accordingly, an excessof film is provided which crinkles in a surprisingly uniform man ner,which crinkled film design is solidified into the surface of the resininterlayer upon gelation and curing thereof. If desired, the film maythen be stripped from the cured resin. Or, it may at times be desirableto leave the films on the product for shipping protection. It will beobvious, of course, that films of other materials which do not producethe desired crinkled finish can be employed on one side of a panel, thecrinkle finish being applied to the other side.

The thermosetting resins employed may include various thermosettingmaterials, such as the polyesters and polyesterstyrene blends, alkydresins, and variations of the synthetic thermosetting materials whichmay be made by one skilled in the art to produce a resin originally in aliquid state which is capable of polymerization to a hard, strong, andsolid mass.

If desirable, various catalysts may be used to aid in curing the resin,and for this purpose organic peroxide catalysts such as methyl ethylketone peroxide, benzoyl peroxide, tertiary butyl perbenzoate and thelike are quite satisfactory. If desired, various promoters oraccelerators known to the art, such as the mercaptans or cobaltnaphthenate, may be used. 7

Films applicable to use in the present invention include those which areattacked by the liquid resin or by atmospheric moisture in a manner suchthat it loses its original fiat form during gelation of the resin.

The preferred film material is cellulose acetate. One cellulose acetatefilm which has proved successful in the production of the presentproducts is that manufactured and sold by the Celanese Corporation ofAmerica under the designation P-904. It has been found that thin filmsof this material are apparently subject to rapid chemical attack by theliquid resin and/or atmospheric moisture and appear to expand whenemployed in the present process. Since the resin interlayer contracts toa relatively great degree, the difference between the contraction ofthe. resin and the apparent expansion of the cellulose acetate filmcreates an excess of film on the surface of the liquid resin interlayerwhich crinkles uniformly and thereby produces a highly decorativecrinkled finish thereon which is retained when the resin is solidified.

It has been found that films of a thickness not exceeding about 0.05inch can be employed in the present invention. Generally, however, filmsof a thickness in the range from about 0.0008 inch to about 0.0019 inchare employed for greatest economy of operation.

Thin films are easier to crinkle than thick films because they are moresubject to atmospheric moisture or chemical attack or partial solutionin a given period of time. Chemical attack or partial solutionapparently causes a softening of the film accompanied by expansion orchange in surface characteristics. The thicker the film, the longer thetime the resin must be held in contact with the film in a liquid stateat a given temperature for the crinkling process to occur. If the filmis too thick for a given set of conditions of temperature and gel time,the film may not crinkle at all, while a thinner film under the sameconditions will crinkle. FIG. of the accompanying drawings shows that acertain acetate film of 0.0015 inch thickness produces a high frequencycrinkle, whereas the same material in 0.005, 0.010 and 0.015 inchthicknesses shows no crinkling, but rather progressive stages ofincipient crinkling.

Film composition also appears to be a factor which affects crinkling.Films of the same thickness but of different compositions exhibitdiifering degrees of or a substantial lack of crinkling under the sameconditions, depending upon the type of plasticizer andother materialsused in their manufacture. For example, a cellulose acetate filmmanufactured by the Celanese Corporation of America and designatedcommercially as L822M provides a medium crinkle when employed in athickness of 0.010 inch. In contrast a cellulose acetate filmmanufactured by the Eastman Kodak Company produces only an incipientcrinkle when used in the same thickness. The Kodak product produced onlyan incipient crinkle even at a thickness of 0.005 inch, under the sameconditions as used in making a crinkle panel with the Celanese 0.010inch product. A comparison of FIGS. 4 and 5 of the accompanying drawingsillustrates this difference of finish.

In the event the product is to be utilized for various structuralelements and it is desired that the product be substantiallytranslucent, a filler or reinforcement consisting essentially of glassin the form of fibers, floc, random mat, or woven cloth may beincorporated in the liquid resin. Such fillers are especially adapted tothe present process and product by virtue of their relatively highstrength-weight ratio. However, other reinforcing materials such asrayon, nylon, certain of the vegetable, synthetic or mineral fibers andthe like may be used.

The product may be shaped and hardened in a wellknown manner and forproducing reinforced structural panels, it has been found that the useof a corrugated lower mold is satisfactory. An upper mold is notgenerally required, but if desired, an aluminum or other light weightcover sheet may be applied over the resin lay-up during the curingoperation. Such a cover sheet serves a two-fold purpose. First, it helpsdistribute heat in a uniform manner to the resin interlayer when a heatsource such as infra-red is applied to the wet lay-up to initiatecuring. Once curing has been started, the resin produces exothermic heatof reaction. Then the cover plate helps to radiate the exothermic heatand stabilize the curing. When the gelling process takes place at a lowhumidity, the cover sheet protects the film from shrinkage by such a lowhumidity condition and allows the chemical action of the resincomponents to affect crinkling of the film.

Temperatures for curing the resin interlayer in the range from about 90F. to about 275 F. will generally be satisfactory. Such curingtemperatures are known in the art. Curing times from about 2 minutes toabout 24 hours or longer may be employed. For commercial efficiency,cure times in the range from about 15 minutes to two hours aredesirable.

Since the crinkling process is essentially one in which the film isaffected in a chemical manner, it is necessary that the resin in contactwith the film be in a liquid form for a time sufficient to produce acrinkle. Once the resin has been cured to a solid form, this chemicalaction of the resin on the film ceases. If the catalysts and/oraccelerators used in the resin, and the temperature employed are suchthat gelation of the resin occurs too rapidly, insufiicient time ofliquid contact with the film may exist to 4. produce a satisfactorycrinkle. By either lowering the temperature or by lowering thecatalyst-accelerator system to increase the gel time, a satisfactorycrinkle can be produced.

Pressures may be used, but they must be limited in order to permit thedesired amount and extent of crinkling of the acetate films. Pressuresless than 2.0 pounds per square inch can be employed, with pressures inthe range from 2 ounces per square foot to 0.5 pound per square inchbeing preferred. The amount of pressure may vary with the type of filmutilized, the curing temperature, and the extent and character of thecrinkled finish desired. If sufiicient pressure is exerted against thefilms encasing the resin interlayer, it may be impossible to produce acrinkle. Accordingly, a substantially fiat or smooth finish results.Under other conditions of excessive pressures, an inverse crinkle mayresult in which the smooth surface plane is higher than the crinkleswhich are formed as valleys rather than ridges. The mechanism ofcrinkling is the same, but the excess film moves inward toward the resinlayer instead of outward.

If desired, the products may be tinted with dyes or pigments of therelatively light-fast type which are not affected by the othercomponents of the resin formulation.

Further, to illustrate the decorative finish provided by the presentinvention, reference may be had to the accompanying drawings, in whichFIG. 1 is a perspective view of a reinforced synthetic resin panel madein accordance with the present invention;

FIG. 2 is an enlarged cross-sectional view illustrating the manner ofpreparing the reinforced resin sheets for the curing step;

FIG. 3 is an enlarged section view of a panel having a crinkled finishand a fiber glass reinforcement;

FIG. 4 is a plan view of a series of panels made by using varyingthicknesses of cellulose acetate films manufactured by the CelaneseCorporation of America; and

FIG. 5 is a plan view of a series of panels made by using varyingthicknesses of a cellulose acetate film manufactured by the EastmanKodak Company.

With reference to the drawings, the numeral 10 indicates a finishedreinforced resin panel, which is here shown by way of example incorrugated form for structural applications, and the reference number 12indicates the crinkles produced by the crinkling of the syntheticorganic film 14 (see FIG. 2). In FIG. 1 the films 14 have been strippedfrom the finished panel 10.

As shown in FIG. 2, the resin interlayer 16, which comprises athermosetting resinous mass 18 having a suitable filler 20 distributedtherein, is placed between the synthetic organic films 14. As shown, theassembly is originally made up in fiat form and is then transferred toan appropriately shaped mold for curing.

Example I As a specific example of a production run of the presentinvention, a thin film of cellulose acetate of 0.001 inch thickness,manufactured by the Celanese Corporation of America and designated asP-904, was laid down on a table. A layer of polyester resin-styreneblend having a catalyst incorporated therein was then flowed onto thecellulose acetate film in a uniform layer approximately of an inch inthickness. A random glass fiber mat was then incorporated into the resinlayer. A second film of cellulose acetate was applied over the resinlayer. The wet lay-up so formed was squeegeed to remove oceluded and wascut into appropriately shaped sections. The cut sections weretransferred to aluminum molds and were covered with light weightaluminum cover or caul sheets of a configuration mating with that of thelower molds. The cover sheets exerted approximately 0.3 pound per squarefoot of pressure to the upper surface of the lay-up. The resin was thencured at an elevated temperature, starting at F. and continuing byincreasing the temperature to 222 F. over a period of /2 hour.

After the curing operation was completed to provide a hardened product,the cellulose acetate films were stripped from the resin-to disclose ahighly decorative crinkled finish on each of the major surfaces of thecured resin, as illustrated in FIG. 4 by the panel designated .001.

Example II A run was made according to the procedure described inExample I except that a cellulose acetate film of .0015 inch thicknessmanufactured by the Eastman Kodak Company was employed. A product havinga uniform and highly decorative crinkled finish on each of the majorsurfaces of the cured resin was produced, as illustrated in FIG. 5, bythe panel designated .0015. The crinkle was uniform but was of somewhatless frequency than that on the product produced in Example I.

Example III A series of runs was made to demonstrate the effect ofvarying thicknesses of cellulose acetate fihns upon the finish, asfollows:

A sheet of cellulose acetate of selected thickness was placed upon asmooth lay-up table and 280 grams of liquid polyester resin was placedthereon to provide a layer approximately li inch thick. The resincomprised a blend of 61 parts polyester resin with 39 parts styrene,

and had 1.0 p.p.h. benzoyl peroxide, 0.5 p.p.h. methyl ethyl ketoneperoxide dissolved in dibutyl phthalate and 0.003 p.p.h. cobaltnaphthena-te, as metal, incorporated therein. A reinforcement of randomfiber glass matof a weight of 2 ounces per square foot was then placed'on the resin and incorporated therein. A second film of celluloseacetate equal in thickness to the first film wasthen placed upon theresin layer. The wet lay-up was squeegeed to remove occluded air and wasthen cured at an elevated temperature. Data for the series are includedin summary form in the following table.

Comparative photographs were taken at equal (1 /2 x) magnifications ofthe surface of each of the panels by employing reflected light. Thesephotos are shown in the accompanying FIGS. 4 and 5. As strikingly shown,a film thickness of less than 0.002 inch produced a uniform crinkledfinish. Film thicknesses of 0.002 inch and over when employing theCelanese film, produced crinkles, but of lesser frequency. Filmthicknesses above .0015 inch produced only incipient crinkling whenemploying the Eastman film.

A careful examination of the surface of the products of the presentinvention represented by the photolithographs designated 00.001 and130.0015 reveals that the crinkle finish contains accumulations orelevations or resin in the order of magnitude of 0.003 inch up to about0.06 inch with an average in the range from about 0.01 to about 0.03inch. Substantially all of these elevations are nearly pure resin withlittle or no reinforcement and comprise 10% or more of the total surfacearea. Observation of the finish of these products discloses that in thecrinkle an excess of resin is drawn to the surface into peaks to coverthe fibrous reinforcement. This would follow from the fact that thereinforcement, such as a glass fiber mat, is interlaced and felted, andbeing positioned generally in the center of the resin interlayer, cannotflow with resin which is drawn outwardly from the main body of resin.This condition is substantiated by the fact that the surface fibers ofthe reinforcement are virtually indistinguishable and visuallyundefinable in the crinkle panels. In panels with a relatively smoothfinish the reinforcing fibers can usually be seen by reflected'light asshown by E005, E015 of FIG. 5.

The feature of excess resin covering the panel surfaces is highlydesirable from the standpoint of weather resistance. The extra resinwhich is drawn up over the fibers in the crinkling'process protects saidfibers against the effects of sun, wind, rain and the like.

By reference to FIG. 3 of the drawings, which represents a cross sectionof a panel 22 made according to the present invention, it will be seenthat the resin rich surface 24 of the crinlsle finish eifectively coversthe fibens 28 so that the fibers are buried deep within the panel undera resin rich, highly decorative, crinkled surface.

As used herein and in the claims the word crinkle may be defined asresin-rich elevations of an amplitude of .003 or more, substantiallyuniformly distributed in a random pattern over the entire surface sothat the area of said elevations comprises more than 10% of the surface.

The invention herein disclosed is particularly adapted for use inconnection with the production of reinforced thermosetting resin panelsfor use as structural materials, and accordingly, examples of thisinvention for the purpose of disclosure are directed toward thatadaptation. However, it is to be understood that the foregoing detaileddescription is given merely by way of illustration for the purpose ofthe disclosure and that many variations may be made therein withoutdeparting from the spirit orf the invention and the scope of thesubjoined claims.

I claim: 1

1. A synthetic resin panel, comprising a substantially rigid sheet ofcured thermoset resin, a plurality of randomly located accumulations ofresin on a major surface of the sheet, the resin accumulations extendingabove the major surface and being integral therewith, and glass fiberswithin the sheet to reinforce the same, the resin accumulations beingsubstantially free of fibers.

' 2. A synthetic resin panel as recited in claim 1, includingadditionally a thin readily removable film intimately in contact withthe major surface and conforming to the resin accumulations.

References Cited in the file of this patent *UNITED STATES PATENTS2,496,911 Green Feb. 7, 1950 2,517,698 Musleat Aug. 8, 1950 2,528,152Landgraf Oct. 31, 1950 2,565,491 Francis Aug. 28, 1951 2,577,205 Meyeret a1 Dec. 4, 1951 2,782,458 Emmert et al. Feb. 26, 1957 FOREIGN PATENTS461,730 Great Britain Feb. 23, 1937

1. A SYNTHETIC RESIN PANEL, COMPRISING A SUBSTANTIALLY RIGID SHEET OFCURED THERMOSET RESIN, A PLURALITY OF RANDOMLY LOCATED ACCUMULATION OFRESIN ON A MAJOR SURFACE OF THE SHEET, THE RESIN ACCUMULATIONS EXTENDINGABOVE THE MAJOR SURFACE AND BEING INTEGRAL THEREWITH, AND GLASS